Reconfigurable and micromachined microwave structures

Abstract

Recent expansion of the wireless infrastructure has led to a dramatic increase in the use of consumer wireless devices. This trend is driving the development of reconfigurable, high performance and inexpensive microwave components. One technology that promises to help meet some of these demands involves the use of periodic structures, also known as electromagnetic band gap (EBG) structures. The use of these EBG structures coupled with micromachining fabrication techniques provides the possibility of producing inexpensive, small and reconfigurable filters that can be used for many microwave applications. With this technology, an electronically reconfigurable EBG crystal has been developed that demonstrates contrast ratios of more than 30 dB between configuration states. This device has led to the development of a microstrip coupled EBG resonator, and then a reconfigurable microstrip coupled EBG resonator. Quality factors on the order of 400 have been demonstrated for these inexpensive and easy to integrate high performance microwave resonators. The first step towards the use of these EBG resonators in a microwave diplexer has been completed. A high performance single pole microwave diplexer has been designed, fabricated and tested using DuroidRTM circuit board material from Rogers Corporation. This diplexer exhibits channel bandwidths of less than 3%, and was used as a test structure for subsequent construction on silicon. Using silicon micromachining techniques the diplexer has been fabricated using silicon wafers. This silicon diplexer has shown improved performance over the Duroid® device in channel bandwidth (<1.6%), insertion loss (<1.5 dB), and channel-to-channel isolation (>26 dB). The development of each of these devices, including the simulated and measured results are be presented along with a discussion of the development path towards a reconfigurable EBG diplexer on silicon.